Method for finishing metal parts



Dec. 7, 1943. G. D. WILD METHOD FOR FINISI'IING METAL PARTS Filed March.30,V 1942 3 Sheets-Sheet 1 Dec. 7, 1943.

G. D. WILD METHOD FOR FINISHING METAL PARTS Filed March 30, 1942 3Sheets-Sheet 2 Dec. 7, 1943. G. D. WILD METHOD FOR FINISHING METAL PARTS3 sheet-sheet s Filed March 30, 1942 Patented Dec. 7, 1943 UNITED STATESPATENT OFFICE METHOD FOR FINISHING METAL PARTS Glenn Donald Wild,Cleveland, Ohio, assignor of one-half to Michael Cisar, Cleveland, Ohio13 Claims.

My invention appertains to the art of finishing metal parts. It dealsprimarily with the provision of a novel method, and a novel machine forcarrying out such method, for effecting a final grinding or finishingtreatment of metal parts which have been pre-ground or pre-machined tocertain fixed general tolerances.

While my invention as described herein is presented primarily withreference to nal fmishing operations on curved surface metal parts tobring them to the finest tolerances that are required for their use, theinvention is equally adapted for use in conjunction with the nishing ofmetal parts with straight or combined fiat and curved surfaces.

My invention has been evolved as a result of the requirements of todayfor increasing production of metal parts and has solved certain problemsof great diiculty incurred by reason of the methods of finishing andmechanical instrumentalities heretofore available for finishing suchparts to the finer tolerances that are being required at this time.

It is well known in the art to which my invention relates that thesurface of metal parts produced by pre-grinding operation, bringing thepart down to the closest tolerances that can be secured by using thegenerally known machines for the purpose desired, the actual finishedsurface referred to, viewed by the naked eye, can be seen to comprisefine feed lines creating projections encircling round metal parts orextending across the surface of fiat metal parts. When the metal partsare further nished, as by the previously described crude processes andas accomplished by my present invention, the said feed lines and allother projections on the surface of the metal, of any nature, areentirely removed to the point of achievement of the final finesttolerances required, and the primary object of my invention has been todevise a method,

land mechanically operated instrumentalities for performing said methodwhereby to greatly facilitate the bringing of the work to the ultimaterequired tolerances above referred to.

In the carrying out of my invention, I avail of a method involving noveltechnique in respect to certain consecutive grinding or finishingactions that are performed upon the work or metal parts, and I utilizeespecially the novel instrumentality of a resilient grinding wheel withwhich to obtain a peculiar function in the grinding or finishingprocess. The said resilient wheel is not only applied to the work byarranging and Workingthe same at special angles, or in peculiar parallelrelation to the axis of the work, but the inherent resiliency of thewheel is availed of in order to effect a variable grinding action uponthe work in respect to different portions of the grinding surface of thewheel. I have found in practice that the said resilient grinding elementas used by me, by being operated so that the greatest pressure isapplied to the Work thereby at the lead portion of the element withlessening pressure toward the trailing portion of the element, willgrind the work in such a way as to reduce the forming of the so-calledfeed lines that I have referred to above, during initial operation ofthe grinding means. Eventually, furthermore, this peculiar variablepressure action of the grinding wheel or element will entirely removethe projection of the feed line and any other projections existing onthe surface of the work as the latter is cut away to bring it to therequired finest tolerances mentioned before.

Another important phase of my method Yand means of accomplishing theresults of my invention lies in the mode of utilizing the choking effectof the ground off particles of metal during the grinding-finishingoperation. In other Words, my method involves the use of the regulatedor controlled choked condition of the grinding element or wheel to Varythe grinding effect produced thereby, said control being obtainedthrough the employment of variable quantities of tallow or equivalentsubstance with which the grinding surface of the grinding Wheel iscoated or treated, as well as by said manipulative technique as respectsthe degree of application of pressure of the grinding Wheel to thesurface being treated or finished.

In reference to the foregoing so-called control of the choking of thegrinding surface of the grinding element by my method, I avail of thephenomenon that the greater the amount of application of tallow to thegrinding surface of the Wheel, the less will be the degree of chokingeffect obtained, and vice versa. In this action, in

other Words, the choking effect may be regulated by reason of thepeculiar quality of the tallow or similar material that may be used tolubricate the surface of the grinding element, and to increase ordecrease, therefore, proportionate with the amount of the said materialused, the ainity between the removed particles of metal ground off ofthe Work and the surfacelof the grinding element. l 1

A further object of my invention, in reference to the method and meansemployed as above` outlined, has been to utilize the resilient grindingwheel or element, in performing its grinding function, to obviate anypossibility of chattering of the wheel during its application to thework, an objectionable feature of the use of hard grinding wheels. Thus,according to the practice of my invention, an advantageous result owsfrom the employment of the resilient grinding wheel in that in the usethereof the balance of the wheel may be quickly changed and thus aperfect balanced condition maintained in the wheel. So far as I amadvised, the foregoing technique of grinding wheel choking and variablepressure effect has never heretofore been employed in the art of metalgrinding, broadly speaking, andirres pective of my specific mode ofutilization of these features of my invention as lhereinafter presented.

My method as above generally utilizedis susceptble of being performed byhand under cer-V tain conditions, one such method being the ernploymentof the hands of the operator to support and move the work in relation tothe grinding wheel with the application of appropriate body o r otherpressure to effect the desired results. Also, said method is susceptibleof being carried out by the use of different types of machines and willpreferably be so performed because greater accuracy, as well as greaterproduction, is possible when machine practice is resorted to. V

In the accompanying drawings I have illustrated one type of machine bywhich the method of my invention may be co-related manually foraccomplishing the method referred to.

In the said drawings:

Figure 1 is a front elevation, somewhat diagrammatic in nature,illustrating the embodiment of my invention in a machine of the enginelathe class wherein many of the lathe parts are utilized after themanner of ordinary lathe operation.

Figure 2 is a vertical section taken approximately on the line 2-2 ofFigure l, looking in the direction of the arrows.

Figure 3 is a horizontal section of a portion of the machine, takenabout Von the line 3--3 of Figure 1'. Y A l Figure 4 is a top plan Viewof the central mechanism of the machine to show more fully the mountingof themotor cradle, grinding wheel, shaft, and carriage for the same,upon the superstructure of the machine.

Figures 5, 6, and? are diagrammatic views illustrating the angulardisposition Vof the work to the grinding wheel during the first, second,and third operations or treatments of the said work, the views beingfront elevations.

Figures 8, 9, and are disposed at one side of Figures 5, 6 and 7,respectively, and diagrammatically illustrate the relation of the workto the grinding wheel duringv the three different operations previouslyreferred to as illustrated by Figures 5, 6, and 7, respectively. InFigures 8, 9, and 10 the dotted line position of the work indicates theposition ofthe same during one traverse of the work across the face ofthe grinding wheel, and the work is illustrated in full lines duringanother traverse thereof across the face of the grinding wheel.

Figure 11 is a greatly exaggerated view 'showing a 'fragmentary portionof the grindingwheel to illustrate its face as acting upon the work,also shown in contact with the facaand the movement of the work Ibeingin the direction of the 'assaut arrow, said view being taken lookingdown upon the wheel and work.

Figure 12 is a view similar to Figure 11 but viewing the parts in frontelevation, the dotted lines showing the approximate formation of thepressure contact area of the work with the face of the wheel.

Figure 13 is a cross sectional view taken about on the line I3--I3 ofFigure 11, the work and grinding wheel brokenaway and bringing out moreclearly the resilient pressure action between the Work and wheel.

In Figures 11 and 12 the dotted lines at the pressure area between thegrinding wheel face and work show approximately the gradually decreasingpressure area from the point of the leading edge to the trailing portionof the face of the wheel.

Figure 14 is a fragmentary View of a grinding wheel having a somewhatdifferent form of grind- Ving face useful for handling of certain typesof work. l

v I shall now describe generally the construction of the one embodimentof a machine illustrated in the drawings designed for the practice ofthe method of my invention.

The engine lathe type machine illustrated in the drawings comprises thebed I supported by the legs 2 and carrying a customary type of headstock3 and tailstock 4. Upon the bed I is mounted the saddle or carriage 5slidable to traverse the bed I in the customary manner of latheconstruction and operated by a motor 6 supported on the carriage, themanner of movement of the carriage being conventional in the art. Inlieu of thecustomary tool rest or support mounted upon the carriage 5, Iprovide a superstructure frame comprising the four corner posts Iconnected at the upper ends thereof by crosspieces 8 arrangedtransversely and longitudinally of the machine. A crosspla-te 9 isconnected at its ends and thereby supported upon the longitudinal crossmembers 8 connecting certain of the posts or standards I of saidsuperstructure frame. The plate 9 forms a support for the outer cradleI0 of inverted U -shape, substantially speaking, which cradle is carriedfrom the plate 9 by the pivotal connection I I, which comprises a screwenabling vthe cradle I0 to be raised and lowered and permitting thepivotal movement of the cradle about said screw las a vertical axis. Thecradle IEI is provided with laterally and downwardly extending ,arms I2at its opposite sides, Awhich arms are pivotally connected at I3 tosimilar arms I4 carried lby an inner motor cradle I5 shaped generallysimilar to the cradle Ill and disposed between the sides of the latter.l

The cradleV I5 may be pivotally moved by reason of the pivotalconnections I3 aforesaid and may be held in adjusted positions aftersuch movement by means of a set screw IS received by -a threaded openingon a side of the inner cradle I5 zand passing through an arcuate shapedopening or slot I'I on the adjacent side of the outer cradle IIJ. Themovement of the inner cradle I5 relatively to the outer cradle I0 may beeiected by a pinion shaft I8 having a handle on its outer end andprotruding through an opening in the side of the cradle Ill. The pinionof said shaft is carried at the inner face of the said outer side of thecradle I9 and meshes with an arc-shaped rack I9 fixed to the adjacentouter face of the inner cradle side.V Simple turning movement of theshaft I8 and its pinion designated I8a will effect relative movement ofthe cradles |10 and l5,

, plate 9. v plate 9 a locking member II a is threadedly en- 'as beingcarried out by hand methods.

V2,336,1fl5 land their proper relative positions when reached foroperation of the machine may be fixed by the set screw I6. The motor 20carried by the inner cradle I5 is mountedk in any suitable mannertherein and `the shaft 2| of said motor has re- `movably attachedthereto the grinding wheel 22.

From the foregoing it will be understood that rthe motor 20 is providedwith a universal mounting by reason of the provision of the pivots I3lconnecting the arms of the cradles III and I5 and by reason of themethod of pivotally supporting the outer cradle I by the pivot member II. The pivots I3 connecting the arms I2 and I 4 of the vcradles asdescribed are adapted to be positioned so as to intersect the horizontalplane coincident with vthe upper surface of the work being operatedupon. Likewise, the grinding wheel 22 is so disposed, by reason -of itsmounting upon Athe shaft 2l, that its face may operate in a verticalplane coincident with the pivotal points I3 of the cradles.

The motor cradle I0 is fixed by any suitable `means to the screw memberI I the said screw l member passing through an opening in the cross-Adjacent the upper surface of the crossgaged with the screw member IIwhereby rota- A suit- I0 from becoming misaligned during operation of`the wheel 22 and to maintain the cradle in the desired adjustment,axially of the screw member II This adjustment may be made during the`movement of the carriage and associated parts yas required by grindingtechnique to be described The machine above referred to is adapted tocarry out the various movements set forth in said process, When certainkinds of work are being finished, by my method.

` In connection with the operating instrumentalities above described inreference to the` superstructure of the machine carried by the carriage5, there will be employed for supporting the shaft 23 which is the Workbeing operated upon, the customary centers 24 and 25. The center 24 iscarried by the usual shaf-t 26 on the headstock 3 and the center 25 bythe usual adjusting screw 27 Von the tailstock 4. The shaft 26 isadapted to be driven by any suitable motor and is equipped with theusual face plate 28 having the lathe dog 29 for coupling to the work todrive the same.

l The motor 20 is capable of rotating the wheel 22 at high speed, andthe spindle 26 of the lathe is adapted to be rotated at a considerablyslower speed to facilitate the grinding action between 4the shaft 23 andthe grinding wheel 22. Under most conditions the shaft 23 is rotated ina direction opposite to the direction of rotation of the wheel 22 tomost effectively produce the finish on the surface of the shaft, inaccordance with the process.

Y Reference is now made to Figures 11 to 13 of the drawings showingprimarily the grinding wheel 22 which, as before stated, is formed of a-resilient body preferably laminated in construction. The face of thewheel 22 is prepared with a grinding surface, and, since differentwheels are -employed for certain of the separate operations to beperformed by my method, said grinding surface is modified accordinglyfor such wheels. The contour of the face of the wheel may likewise be'modified t0 take different forms, one of which l is illustrated inFigure lfi of the drawings, sald .contour depending upon the kind ofwork to be ywheel structure, it is notable that in the practice of mymethod there are utilized three method steps of grinding, and thegrinding wheel employed for each step is differently prepared on itsgrinding face because of the nature of the work to be performed by eachstep of the process.

Describing the grinding wheel as prepared for the first step of myprocess, it is notable that I utilize for the face of the wheel arelatively coarse #320 emery. The term relatively as above used, ismerely employed for purposes of comparison, because the emery isobviously fine-grained. The `said emery is applied to the face of thewheel by the use of a suitable glue or adhesive. In a similar manner theemery wheel or wheels used for the second step of my process are set upwith #400 emery and the Wheel or wheels used in the third step of theprocess are set up with #500 grain emery.

Referring now to Figures 5 to 10 inclusive of the drawings, the methodof my invention will be described as it may be performed by hand and inrelation to the further preparation of the emery wheels used at eachstep of the process for carrying out such step.

In Figures 5 and 8 my first process step is depicted diagrammatically,and it is to be understood that the work 23 may be held in the hands ofthe operator and caused to be pressed against the grinding wheel 22 bymanual pressure, including body pressure as may be necessary. As viewedfrom the front elevation of Figure 5, the work or shaft 23 is disposedata vertical angle to the face of the Wheel 22 approximately 30preferably, and said shaft is carried across the face of the Wheel inone direction to enable the latter to perform its grinding operationthroughout the area of the surface which is being finished, In the aboveaction the wheel causes the rotation of the work in the hands of theoperator who will, by means of his hands, retard the turning ted linesin Figure 8 while the vertical angle remains substantially the same andthe work is then carried in the opposite direction. In the aboveoperation, the shaft or work 23 is pressed against the left portion ofthe peripheral face of the wheel 22 as the Work is carried rightward,and then, when the work is moved on the reverse stroke, it is pressedagainst the right peripheral portion of the face of the wheel. Now it isunderstood that the wheel as used in the step just described is that setup with #320 grain emery. According to my process, furthermore, as theWork 23 is carried .across the face portion of the wheel 22, see Figure11, in the direction of the arrow, the leading edge of the resilientwheel 22 is pressed against with the greatest force and the pressurealong the trailing portion of the face gradually diminishes because ofthe contour of 'the face, the resiliency of the wheel, and the angies atwhich the work is presented to the face of the wheel.

f The foregoing is also true in relationV tov the movement of the workreversely to that described and in a position reversely to thatillustrated in Figure 11 and more clearly shown by the dotted 'lineposi-tion ofthe work in Figure 8. In the operation as described inFigures 5, 8, andv l1 above given, it is obvious that the feed linesshown on the work in Figure 11 designated `3l] are substantiallyperpendicular to the surface of the work or piece 23 as defined thereonby previous action in thepre-grinding operation referred to, and whenthe work is presented to the face of the grinding wheel 22 as above setforth and permitted to rotateincontact therewith, the said feed lines 30are'acted upon by the emery on :the face of the wheel 22 in a graduallydecreasing amount as the pressure of the face of the wheel on the workdecreases. In other words, at the point of contact of the work 23 withthe wheel 22 `shown in Figure 11, the same being Vthe leading edge ofthe wheel, designated a, the amountI of cutting at this point by theemery on the face will be greatest in View of the fact that the greatestpressure is exerted at this point and the wheel affords the greatestresistance at the said point. From the foregoing it will be seen thatthe pressure diminishes as the surface contact of the sides of the wheelwith the Work 23 decreases due to the angularity with which the work ispresented to the wheel and to the conformation of the face of the wheel,the said pressure decreasing to a point somewhere lsubstantially beyondthe center of the wheel "where it is no longer effective to perform thecutting or grinding operation, thereby becoming zero since the face ofthe wheel no longer contacts the work piece. This effectively preventsthe formation of a trailing line or an additional feed line that wouldnormally prevail if Vfull surface contact of the face of the wheel withthe work obtained. In Figure 12 the surface contact of the wheel face isillustrated in dotted lines'ove'r the pressure area on the work or'piece 23 as 'presented in Figure 11, and from this view it will befully noted that the pressure area de- "creases to the zero or minimumpoint at the end for junction of said dotted lines, designated l), andthereafter, since there is no contact of `the face of the wheel with thework as previously set forth, there is no pressure area shown.

In Figure 13, a view taken as previously explained on the line f3-l3 ofFigure 11, the ac- -tual contact of the portion of the wheel perform-ving the grinding operation is sho-wn in vsomewhat exaggerated manner asfollowing the contour of the Work being operated on throughout thelcontact of Ythe face of the wheel therewith, and is seen to be areverse curve to that of the normal contour of the vwheel periphery,and, Yas is apparent, the periphery assumes that normal contour after ithas performed its lcutting yoperation and thereafter retains the propercircumferential relationship until again presented to the work for thecutting operation at the end of a Complete revolution of the wheel. Thisis vdue to the inherent resiliency of the wheel structure, and thisresiliency vhas been availed of by me in an entirely new way for thepurposeof grinding metal parts, so far as I am aware.

During the operation of the first step, asabove described, the face ofthe wheel :is prepared by lapplying tallow (grease stick), or anequivalent material thereto,"very freely, and the quantity ofY tallowvof free application, as above referred to, is maintained throughout thereverse move- 'Imentsof the workh'eld at the proper angles stated. Thereason for freely applying the tallo'w as above described is to avoidthe choking ofthe wheel face with the metal particles removed by thegrinding action of the emery on the face, the tallow, practicallyspeaking, providing a lubricant for retarding or preventing 'theadhesion of the said metal particles to the face and to the intersticesbetween the emery grains. f

I pass now to the second stepv of my process, which is virtually arepetition of the method of presenting and moving the work across thevface 'first operation on the surface of the work. In

this second step of operation of my method the #400 grain emery wheel isemployed as previ- 'ously indicated, and of course by the second stepany feed lines left on the surface of the work are reduced in number andin size by the grinding yeffect produced. However, 'it is to beunderstood that in the second step I utilize choking of the wheel forobtaining the ner grinding action that is desired in such step.Therefore, the operator will apply the tallcw sparingly in this secondstep, as compared with the first step, so as to let the metal particlesor nes ground olf the work partially ll into the face of the grindingwheel and the interstices between the grains for effecting the aboveimportant -second step of operation.

'Referring now to the third step of the operation of my method, Figuresl and l0 of the drawings are illustrative. The work at this period ofthe method is -supposed know to be clean down to vthe true grain Yof themetal and therefore in this third step VI employ a #500 grain emerywheel face and the same type resilient wheel as stated with reference tothe first two steps. Likewise vin this third step the tallow is sosparingly used, much more so than in the second step described, as tocompletely or valmost completely permit choking of the wheel and thisaction may be enhanced somewhat `by the employment of a little rosin orrouge. Such treatment of -rthe wheel face by the tallow with Yutmostsparing necessarily r'promotes the affinity between the face and the-metal particles Vground off the work, affording the desired adhesion tosubstantially fully choke the face in the manner in which thisterminology is employed in this specification. According to the-operation-ofthe third step nowdiscussed, it

Vis contemplated that the work shall be carried across the face of theWheel in a horizontal plane --substantially Yparallel with the plane ofthe axis movement :in opposite directions, depicted by Figure 1'0.

In the third and `last step of my method as above set forth, the 'vnaltolerance necessary-for the na'l grinding or completion of lthe Work Tisobtained andthe grinding action straightens out the cross-grains on themetal surface of the work and brings the latter to the ultimate finishedcondition for use, at which time it reaches the true color of the metal.

It is within the purview of my invention, dependent upon the tolerancesthat are required for the finished metal parts treated according to thepractice above described, that I may use the practice of one or acombination of any two of the steps recited, but it is important andessential that the grinding wheel shall be resilient and shall beconstructed `and treated substantially in the manner set forth.

Ihave described the iineness of the emery employed for the differentgrinding wheels of the different steps in the sense of relativity of thesizes of the grains employed and do not wish to be bound to the exactsizes because the grains for each step may be varied somewhat within adesired range of same most suitable for the work to be performed by thatparticular step.

By the practice of the method above set forth, either manual or by theperformance of a machine such as hereinafter described, I haveaccomplished a tremendous saving of time in the finishing of metal partsof different types or kinds, and I have eliminated a great quantity ofwast-age or spoilage that has heretofore been incident to the finishingof such parts to obtain the tolerances referred to herein as susceptibleof being achieved, as compared with previously known methods commonlybeing used today.

Also, the practice of my invention has been adopted andused extensivelyin the manufacture of metal parts required to be finished to suchtolerances as have been secured according to the foregoing description,and which metal parts have been of great consequence and importance tothe machines wherein they are used.

Referring to Figures 1 to 4 of the drawings and the machine thereinillustrated for the practice of the method of this invention, `it willbe very evident that the work or shaft 23 supported in said m-achine isdisposed to turn about a predetermined axis and therefore is notsusceptible of being shifted as is the work illustrated in Figures 5 to10 of the drawings when manually supported. The design of my machineaforesaid contemplates that the grinding wheel 22 shall be operated andshall be adjusted for angular dispositions both vertically andhorizontally to perform its grinding action upon the work or shaft 23.It is obvious, according tothe showing in Figure 1 that the grindingwheel 22 may be caused to take the positions of relative angularity tothe work as depicted by Figures 5, 6, 8 and 9 of the drawings, and islikewise capable of having its face presented to the Work while the axisof the wheel is in a horizontal plane parallel to the axis of the work.The universal mounting of the motor cradle I5 is the means whereby thewheel 22 may be shifted along with the motor shaft to present the faceof the wheel at the desired angles according to the method depicted inFigures 5 to 10 and described'above. Of course, in conjunction with saiduniversal mounting, the tilting of the motor shaft 2| by tilting of thecradle I5 within the cradle Ill also permits of the desired adjustmentsof the grinding wheel 22 necessary for the practice of the method.

Since it is the adopted practice, according to the method of myinvention, generally to. check the diameter of the work or the amount ofmetal ground off the surface of the work periodically,

it is easy for the operator o f the machine to effect the desiredangular adjustments of the wheel or the adjustment illustrated in Figure9 between the work checking operations and at the end of the traverse ofthe carriage 5 with the superstructure framework in which the motor ismounted.

The manner of effecting horizontal and vertical angular adjustment ofthe shaft and wheel in the machine described, to carry out the methodpreviously set forth, is readily understood by reference to Figure 1.

During the traverse of the carriage 5 in a left Ward direction, the axisof the wheel 22 is tilted forwardly by means of loosening the set screwI6 and manipulation of the pinion IBa, the contact of the periphery ofthe wheel being thereby similar to the contact illustrated in Figure 8.This angular relationship was referred to previously as the horizontalangular adjustment, but it is apparent that in the use of the machine tocarry out my process, when the wheel is adjusted, and the shaft beingfinished is supported for rotation on fixed centers, this change is avertical angular change. Similarly, the vertical angular shifting of thewheel respecting the work now becomes a horizontal angular relationshipaccomplished by rotating the motor and wheel about the screw member I Ias a pivot. The wheel thus assumes the position respecting the shaft, asshown in Figure 5. i

Traverse of the carriage 5 in a rightward direction will necessarilyinvolve shifting of the wheel 22 respecting the shaft as illustrated inFigure 8, the shaft being then in the dotted line position in thatfigure.

'Ihe procedure with the grinding wheels of steps two and three,illustrated in Figures 6 and 9, and 7 and 10, respectively, will beVcarried out in the manner previously described, the wheel being shiftedand traversing the shaft or work on the machine, as contrasted withmovement of the shaft and shifting of the same respecting the wheel, asset forth in the hand method.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

l. The method of finishing metal parts, which includes presenting thework to the face of a resilient faced grinding wheel with the workdisposed at a vertical angle to the resilient face and likewise disposedat a horizontal angle thereto, effecting a relative bodily movement ofthe wheel and work while the latter is so disposed and pressed against aleading edge of the face of the wheel, thereupon reversing the relativemovement of the wheel and work after reversing the horizontal angle ofthe work respecting the wheel to maintain the work in pressure .contactwith another leading edge of the face of said wheel, and causingmovement of the work and wheel at different relative speeds at theircontacting portions.` 1

2. The method of finishing metal parts, which includes presenting thework to the face of a resilient faced grinding wheel with the workdisposed at a vertical angle to the resilient face and likewise disposedat a horizontal angle thereto, effecting a relative bodily movement ofthe wheel and work while the latter is so disposed, exerting acontacting pressure of the said wheel face and work such that thepressure is greatest at the leading edge of the face and diminishestoward the trailing portion of the face, thereupon revers` ing therelative movement of the wheel and work after reversing the saidhorizontal angle of the work, and maintaining the same character ofpressure contact of the work and wheel face dur.- ingsuch reversedmovement, and causing movement of the work and wheel at differentspeeds.

3. rhe method of finishing metal parts, which includes pressing the Workagainst the face of a resilient faced grinding wheel with greatestpressure at the leading edge of such face and gradually4 diminishingaway from said leading edge toward the trailing portion ofthe wheelface, causing relative bodily movement of'said wheel and work in onedirection, then reversing the direction of relative bodily movement ofthe work and face while maintaining the same character of diminishingpressure of the wheel and work from the leading edge of the wheel face,and causing different speeds of movement of the wheel and work at theircontacting portions during the said opposite bodily movements.

e. The method claimed in claim 3, wherein the work is disposed at ahorizontal angle to the wheel face during relative bodily movement inone direction, and ata reversed horizontal angle when the relativebodily movement is performed in the opposite direction.

5. The method of nishing metal parts, which includes applying tallowfreely to the face of a resilient grinding wheel to avoid choking,pressing the work against the face of the resilient faced grinding Wheelwith greatest pressure at the leading edge Vof such face and graduallydiminishing away from said leading edge toward the trailing portion ofthe wheel face, causing relative bodily movement of said wheel and workYin one direction, then reversing the direction of relative bodilymovement of the work and face while maintaining the same character ofdiminishing pressure ofthe wheel and work from the leading edge ofthewheel face, and causing different speeds of movement of the wheel andwork at their contacting portions during the said opposite bodilymovements.

6. The method of finishing metal parts, which includes applying tallowsparingly to the face of a resilient grinding wheel to regulate itsaction by partial choking, pressing the work against the face of theresilient faced grinding wheel with greatest pressure at the leadingedge of such face and gradually diminishing away from said leading i'edge toward the trailing portion of the wheel face, causing relativebodily movement of said wheel and work vin one direction, then reversingthe direction of relative bodily movement of the work and face whilemaintaining the same character of diminishing pressure of the wheel andwork from the leading edge of thewheel face, and causing differentspeeds of movement of the wheel and work at their contacting portionsduring the said opposite bodily movements.

'7. The method of finishing metal parts, which includes applyingtallovir so sparingly to the face of a resilient grinding wheel that theface will be choked by metal particles ground from the work, pressingthe work against the face of a resilient faced grinding wheel withgreatest pressure atV the .leading edge of such face and graduallydiminishing away from said leading edge toward thetrailing portion ofthe wheel face,l causing relative bodily movement of said wheel and workin one direction, then reversing the direction of relative bodilymovement of the work and face while maintaining the same character ofdiminishing pressure of the wheel and work from the leading vedge oflthe wheel face, and causing different speeds of movement of the wheeland Work at their contacting portions during the said opposite bodilymovements.

8. The method of nishing metal parts which includes as a first step ofoperation, presenting the work to the face of a resilient faced grindingwheel with the work disposed at a vertical angle to the resilient faceand likewise disposed at a horizontal angle thereto, effecting arelative bodily movement of the wheel and work while the latter is sodisposed and pressed against a leading edge of the face of the Wheel, asecond step of operation reversing the relative movement of the wheeland work after reversing the horizontal and vertical angles of the workrespecting the wheel to maintain the work in pressure contact withanother leading edge of the face of said wheel, and causing movement ofthe work and, wheel at different relative speeds at their contactingportions during said steps.

9. The method of finishing metal parts which comprises, a rst step ofoperation of presenting the work to the face of a resilient facedgrinding wheel with the work disposed at a vertical angle to theresilient face and likewise disposed at a horizontal angle thereto,eiecting a relative bodily movement of the wheel and work while thelatter is so disposed and pressed against a leading edge of the face ofthe wheel, a second step of reversing the relative movement of the wheeland work after reversing the horizontal and vertical angles of the workrespecting the wheel to maintain the work in pressine contact withanother leading edge ofthe face of said wheel, and a third step ofoperation comprising presenting the Work to the face of the wheel withthe work disposed in 'a horizontal plane parallel with the axis of thewheel, and at a horizontal angle with respect to said face, effecting arelative bodily movement oi the wheel and work while the latter is sodisposed and pressed against a leading edge of the, face of the wheel,thereupon reversing the relative movement of the wheel and Work afterreversing the horizontal angle of the work respecting the wheel, tomaintain the work in pres sure contact with another leading edge of theface of said wheel, and causing movement of the Work and wheel atdiiferent relative speeds at their contacting portions during saidsteps.

10. The method of finishing metal parts, which includes presenting thework to the face of a resilient faced grinding wheel with the workdisposed at a vertical angle to the resilient face and likewise disposedat Ia horizontal angle thereto, applying tallow freely to the face ofthe wheel, effecting a relative bodily movement of the wheel and workwhile the latter is so disposed and pressed against a leading edge ofthe face 0f the wheel, thereupon reversing the relative movement of thewheel and work after reversing the horizontal and vertical angles of thework respecting the wheel to maintain the work in pressure contact withanother leading edgerof the face of said Wheel, applying tallow to theface of the wheel in such measure as to effect regulated partial chokingof the wheel face, and causing movement of the work and wheel atdifferent relative speeds at their contacting portions.

11. The method of nishing metal parts, which comprises a iirst step ofoperation including presenting the work to the face of a resilient facedgrinding wheel with the work disposed at a vertical angle to theresilient face and likewise disposed at a horizontal angle thereto,applying tallow freely to the face of the wheel and effecting a relativebodily movement of the wheel and work while the latter s so disposed andpressed against a leading edge of the face of the wheel, a second stepincluding reversing the relative movementl of the wheel and work afterreversing the horizontal and Vertical angles of the work respecting thewheel to maintain the work in pressure contact with another leading edgeof the face of said wheel, and applying tallow to the face of the wheelin such measure as to effect regulated partial choking of the face, anda third step of operation including presenting the Work to the face ofthe wheel with the work disposed in a horizontal plane parallel with theaxis of the wheel, effecting a relative bodily movement of the wheel andwork while the latter is so disposed and pressed against a leading edgeof the face of the wheel, thereupon reversing the relative movement ofthe wheel and work after reversing the horizontal angle of the workrespecting the Wheel, to maintain the work in pressure contact withanother leading edge of the face of said wheel, applying tallow to thewheel face during the third step so sparingly as to permit full chokingof said face in its grinding action, and causing movement of the workand wheel at different relative speeds at their contacting portionsduring all of said steps.

12. The method of nishing metal parts which includes as a rst step ofoperation, including presenting the Work to the face of a resilientfaced grinding wheel with the work disposed at a vertical angle to theresilient face and like- Wise disposed at a horizontal angle thereto,said wheel having a relatively coarse abrasive on the face thereof,effecting a relative bodily movement of the wheel and work while thelatter is so disposed and pressed against a leading edge of the face ofthe wheel, a second step of operation of reversing the relative movementof the wheel and work after reversing the horizon-j tal and verticalangles of the work respecting the Wheel to maintain the work in pressurecontact with another leading edge of the face of said wheel, said wheelface having a relatively iiner abrasive thereon than in said rst step,effecting a relative bodily movement of the wheel and work while thelatter is so disposed and pressed against a leading edge of the face ofthe wheel, and causing movement of the Work and Wheel at dilerentrelative speeds at their contacting portions during said steps.

13. The method of iinishing metal parts which comprises, a rst step ofoperation of presenting the Work to the face of a resilient facedgrinding wheel with the work disposed at a vertical angle to theresilient face and likewise disposed at a horizontal angle thereto, saidwheel having a relatively coarse abrasive on the face Y thereof,effecting a relative bodily movement of the wheel and work while thelatter is so disposed and pressed against a leading edge of the face ofthe wheel, a second step of reversing the relative movement of the wheeland Work after reversing the horizontal and vertical angles of the workrespecting the Wheel to maintain the work in pressure contact withanother leading edge of the face of said Wheel, said wheel face having arelatively finer abrasive thereon than in said rst step, and a thirdstep of operation comprising presenting the work to the face of theWheel with the Work disposed in a horizontal plane parallel with theaxis of the wheel and at a horizontal angle with respect to said face,said wheel face having a ner abrasive thereon than those used inprevious steps of operation, eiecting a relative bodily movement of thewheel and work while the latter is so disposed and pressed against aleading edge of the face of the wheel, thereupon reversing the relativemovement of the wheel and work after reversing the horizontal angle ofthe work respecting the wheel, to maintain the work in pressure contactwith another leading edge of the face of said wheel, and causingmovement of the work and Wheel at different relative speeds at theircontacting portions during said steps.

GLENN DONALD WILD.

